The Food and Drug Administration told the manufacturer of a new leukemia drug called Iclusig to stop marketing and selling the medicine because of an increasing number of strokes, heart attacks and other serious side effects.

The drug from Ariad Pharmaceuticals Inc. was approved just last December under an FDA process called accelerated approval, in which a manufacturer needn't prove a survival advantage for patients. It can start marketing the drug by showing improvements in other measures short of survival—in Iclusig's...